Advances in weapon systems technology have enabled some weapon systems to discriminate targets based on target signatures. As a result, evaluating and/or deceiving these types of sophisticated weapon systems have become increasingly difficult.
Various methods are currently used to evaluate weapon systems. These evaluation methods include computer modeling, hardware-in-the-loop (HIL), and flight testing. Currently, the evaluation method that is chosen for use depends on the development stage of the weapon systems to be evaluated. However, only during flight tests are a missile's kinematics, target tracking, and counter electronic countermeasures (counter ECM) performance capabilities fully exercised and evaluated.
A lack of targets available for weapon systems evaluation exists because of practicality and cost constraints. For example, no bomber aircraft are available in current U.S. inventories for use as targets in evaluating employment of modern weapon systems against bomber aircraft.
This lack of target assets forces weapon evaluators to use similarly-sized surplus assets and/or subscale drones that employ means for enhancing their signatures to levels representative of actual targets. For example, subscale drones currently are used for over 90% of missile evaluation flight tests. However, because of relatively high acquisition and maintenance costs, a full-size target, such as a QF-4, is available for only a small percentage of flight tests. Even when such a target is used, its signature remains that of the actual airframe used—and not that of an actual threat, such as a Backfire bomber or a MIG-29 interceptor or a Mirage fighter or the like. Moreover, because of its large and complex structure and span, a bomber offers unique challenges for missile tracking algorithms.
One approach to overcoming such a lack of target assets might be to mechanically modify available assets like subscale drones. However, relatively small physical characteristics of available assets do not provide target signature levels and fidelity that are representative of full-sized fighter and bomber targets. Lowered signal strength and fidelity restrict a missile's ability to engage such a target at long ranges, thereby lessening severity of performance-degrading effects on the missile that are typically associated with the signature of a full-size target at close ranges. Similarly, current decoys lack sufficient signature fidelity, thereby enabling advanced enemy weapon systems to reject the decoys during battlefield engagement.
Currently, long-range engagement deficiencies are addressed by employing passive reflectors, such as a Luneberg lens, or a corner reflector, or a simple active repeater (beacon). While these techniques are acceptable for crew training exercises, they are not suitable for missile evaluation purposes. A passive reflector or a beacon provides a relatively steady-state point source over a specified angular region, thereby artificially enhancing ability of the missile to track the target at long and short distances.
Such steady-state signals do not exhibit complex modulations, that are inherent in the signature of a full-size target, to stress the missile's performance envelope. A complex target, such as a bomber aircraft, introduces various forms of modulation onto an illuminating radar's signal. The type of modulation introduced is aspect dependent. These modulations include radar cross section (RCS), amplitude modulation (scintillation), phase/Doppler modulation (et engine modulation, or JEM), angular modulation (glint), polarization modulation, and time modulation (range noise). Each type of modulation produces undesired effects on the engaging missile. Different missiles employ different techniques and software algorithms to lessen or eliminate negative effects caused by these modulations.
Therefore, it would be desirable to simulate a variety of threat aircraft with a sufficiently high fidelity level for a realistic evaluation of weapon systems.